Simplified spring load mechanism for delivering shaft force of a surgical instrument

ABSTRACT

A connection mechanism and manufacturing method for a surgical instrument includes an inner shaft member that extends at least partially through an elongated shaft member of the instrument and defines proximal and distal ends and is selectively movable in a longitudinal direction with respect to the elongated shaft member and includes at least one aperture that extends partially along the longitudinal direction and disposed distally from the proximal end. The inner shaft member enables a drive collar member to slide on the inner shaft member and reciprocate along the longitudinal direction. A drive collar stop member slides on the inner shaft member and moves along the longitudinal direction. The drive collar stop member then moves in a direction relative to the longitudinal axis to engage the aperture and limit further longitudinal motion of the drive collar member. An inner shaft stop member limits movement of the inner shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/858,368, filed on Sep. 18, 2015, which is a continuation of U.S.patent application Ser. No. 14/036,238, filed on Sep. 25, 2013, now U.S.Pat. No. 9,668,807, which is a continuation-in-part of U.S. patentapplication Ser. No. 13/461,335, filed on May 1, 2012, now U.S. Pat. No.9,820,765, the entire contents of each of which are incorporated hereinby reference.

INTRODUCTION

The present disclosure relates generally to the field of surgicalinstruments. In particular, the disclosure relates to an endoscopicelectrosurgical forceps that is economical to manufacture and is capableof sealing and cutting relatively large tissue structures. The presentdisclosure relates also to connection mechanisms to actuate the jawmembers of a surgical instrument.

BACKGROUND

Instruments such as electrosurgical forceps are commonly used in openand endoscopic surgical procedures to coagulate, cauterize and sealtissue. Such forceps typically include a pair of jaws that can becontrolled by a surgeon to grasp targeted tissue, such as, e.g., a bloodvessel. The jaws may be approximated to apply a mechanical clampingforce to the tissue, and are associated with at least one electrode topermit the delivery of electrosurgical energy to the tissue. Thecombination of the mechanical clamping force and the electrosurgicalenergy has been demonstrated to join adjacent layers of tissue capturedbetween the jaws. When the adjacent layers of tissue include the wallsof a blood vessel, sealing the tissue may result in hemostasis, whichmay facilitate the transection of the sealed tissue. A detaileddiscussion of the use of an electrosurgical forceps may be found in U.S.Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodesdisposed on clamping faces of the jaws. The electrodes are charged toopposite electrical potentials such that an electrosurgical current maybe selectively transferred through tissue grasped between theelectrodes. To effect a proper seal, particularly in relatively largevessels, two predominant mechanical parameters must be accuratelycontrolled; the pressure applied to the vessel, and the gap distanceestablished between the electrodes.

Both the pressure and gap distance influence the effectiveness of theresultant tissue seal. If an adequate gap distance is not maintained,there is a possibility that the opposed electrodes will contact oneanother, which may cause a short circuit and prevent energy from beingtransferred through the tissue. Also, if too low a force is applied thetissue may have a tendency to move before an adequate seal can begenerated. The thickness of a typical effective tissue seal is optimallybetween about 0.001 and about 0.006 inches. Below this range, the sealmay shred or tear and above this range the vessel walls may not beeffectively joined. Closure pressures for sealing large tissuestructures preferably fall within the range of about 3 kg/cm2 to about16 kg/cm2.

Additionally, prior art surgical instruments include connectionmechanisms for actuation of distal end components such as jaw memberswhere the connection mechanisms require several manufacturing steps suchas attaching a mandrel to an inner shaft member with correspondingnumber of parts required. Misalignment of the parts may result in aninconsistent and/or inadequate delivery of the shaft force required foractuation.

As is traditional, the term “distal” refers herein to an end of theapparatus that is farther from an operator, and the term “proximal”refers herein to the end of the electrosurgical forceps that is closerto the operator.

SUMMARY

The present disclosure relates to an electrosurgical apparatus andmethods for performing electrosurgical procedures. More particularly,the present disclosure relates to electrosurgically sealing tissue.

The present disclosure describes a surgical instrument for treatingtissue that is economical to manufacture and is capable of sealing andcutting relatively large tissue structures.

The surgical instrument includes an elongated shaft having a distalportion and a proximal portion coupled to a housing. The elongated shaftdefines a longitudinal axis. An inner shaft member extends at leastpartially through the elongated shaft. The inner shaft member isselectively movable in a longitudinal direction with respect to theelongated shaft. An end effector adapted for treating tissue issupported by the distal portion of the elongated shaft. The end effectorincludes upper and lower jaw members pivotally coupled to the distalportion of the elongated shaft about a pivot axis. The upper and lowerjaw members include a first and second pair of laterally spaced flanges,respectively. The first and second pairs of flanges of the jaw membersare arranged in an offset configuration such that one flange of theupper jaw member is positioned on a laterally exterior side of acorresponding flange of the lower jaw member, and the other flange ofthe upper jaw member is positioned on a laterally interior side of theother flange of the lower jaw member.

Additionally or alternatively, the housing includes a movable actuatingmechanism configured to cause longitudinal movement of the inner shaftmember relative to the elongated shaft.

Additionally or alternatively, the elongated shaft includes at least onefeature formed therein configured to operably engage the movableactuating mechanism.

Additionally or alternatively, the elongated shaft has a generallycircular profile joined along two opposing longitudinal edges.

Additionally or alternatively, the two opposing longitudinal edges arelaser welded together.

Additionally or alternatively, the two opposing longitudinal edges arejoined by one of a box joint interface and a dovetail joint interface.

Additionally or alternatively, the surgical instrument includes a campin supported by the inner shaft member such that longitudinal movementof the inner shaft member is imparted to the cam pin.

Additionally or alternatively, each of the first and second laterallyspaced flanges define a camming slot for engaging the cam pin.

Additionally or alternatively, the upper and lower jaw members areconstructed as substantially identical components positioned in alaterally offset manner with respect to one another.

Additionally or alternatively, the pivot axis extends through each ofthe flanges in a direction substantially transverse to the longitudinalaxis.

Additionally or alternatively, the inner shaft member extends throughthe jaw members on a laterally interior side of each of the flanges.

Additionally or alternatively, the surgical instrument includes a knifeselectively movable in a longitudinal direction with respect to theinner shaft member.

Additionally or alternatively, the inner shaft member includes a knifeguide disposed on a distal end of the inner shaft member such that theknife is substantially surrounded on four lateral sides.

According to another aspect of the present disclosure, a surgicalinstrument is provided. The surgical instrument includes an elongatedshaft including a distal portion and a proximal portion coupled to ahousing. The elongated shaft defines a longitudinal axis. An endeffector adapted for treating tissue is supported by the distal portionof the elongated shaft. The end effector includes first and second jawmembers pivotally coupled to one another to move between open and closedconfigurations. Each of the jaw members includes a pair of laterallyspaced flanges. Each of the flanges includes a camming surface. A knifeextends at least partially through the elongated shaft and isselectively movable in a longitudinal direction between the flanges ofthe jaw members. A blade of the knife is extendable into a tissuecontacting portion of the jaw members. An inner shaft member extends atleast partially through the elongated shaft and is selectively movablein a longitudinal direction with respect to the knife and with respectto the elongated shaft. The inner shaft member carries a cam pinpositioned to engage the camming surface of each of the flanges toinduce the jaw members to move between the open and closedconfigurations.

Additionally or alternatively, the elongated shaft includes at least onefeature defined therein configured to engage a movable actuatingmechanism operably associated with the housing.

Additionally or alternatively, the laterally spaced flanges of the jawmembers are arranged in a nestled configuration wherein both of theflanges of one of the jaw members are arranged within a laterallyinterior side of the laterally spaced flanges of the other of the jawmembers.

According to another aspect of the present disclosure, a method ofmanufacturing a surgical device including a housing and an elongatedshaft for coupling an end effector with the housing of the surgicaldevice is provided. The method includes the steps of stamping at leastone feature into a blank of sheet metal and folding the blank into suchthat two opposing longitudinal edges of the blank meet at a longitudinalseam to form an elongated shaft. The method also includes the step ofoperably coupling an end effector to at least one feature formed at adistal portion of the elongated shaft. The method also includes the stepof engaging at least one actuating mechanism supported by a housing withat least one feature formed at a proximal portion of the elongated shaftto operably couple the proximal portion of the elongated shaft with thehousing. The actuating mechanism is configured to selectively move theend effector between an open position and a closed position.

Additionally or alternatively, the method includes the step of joiningthe two opposing longitudinal edges along the longitudinal seam.

Additionally or alternatively, the joining step further comprises laserwelding the longitudinal seam. The longitudinal seam may be a box jointconfiguration or a dovetail joint configuration.

Additionally or alternatively, the method includes the step of couplinga drive rod to the at least one actuating mechanism at a proximal endand to the end effector at a distal end. The drive rod may be configuredto translate within and relative to the elongated shaft upon movement ofthe at least one actuation mechanism to effect actuation of the endeffector.

Additionally or alternatively, the method includes the step of stampingat least one feature at a distal end of the blank such that a clevis isformed at a distal end of the elongated shaft. The clevis may beconfigured to support the end effector.

According to another aspect of the present disclosure, a connectionmechanism for a surgical instrument is provided. The connectionmechanism includes an inner shaft member that is configured to extend atleast partially through an elongated shaft member of a surgicalinstrument and that defines proximal and distal ends. The inner shaftmember is selectively movable in a longitudinal direction with respectto the elongated shaft member. The inner shaft member includes at leastone aperture defined therein and that extends partially along thelongitudinal direction of the inner shaft member and that is disposeddistally from the proximal end. The inner shaft member is configured toenable a drive collar member to slide on the inner shaft member andreciprocate along the longitudinal direction of the inner shaft member.A drive collar stop member is disposed to slide on the inner shaftmember and to move along the longitudinal direction of the inner shaftmember. The drive collar stop member moves in a direction relative tothe longitudinal axis defined by the inner shaft member to engage the atleast one aperture and limit further longitudinal motion of the drivecollar member.

Additionally or alternatively, the connection mechanism may furtherinclude a drive collar member disposed to slide on the inner shaftmember, wherein the drive collar member is movable along thelongitudinal direction of the inner shaft member, and wherein the drivecollar member is configured such that further longitudinal motion of thedrive collar member is limited upon engagement of the drive collar stopmember with the at least one aperture.

Additionally or alternatively, the inner shaft member may include atleast one additional aperture defined therein and that extends partiallyalong the longitudinal direction of the inner shaft member and that isdisposed proximally of the at least one aperture. The at least oneadditional aperture is configured to enable an inner shaft stop memberto slide on the inner shaft member and to move along the longitudinaldirection. The at least one additional aperture may be configured toenable the inner shaft stop member to engage and limit movement of theinner shaft member along the longitudinal axis following insertion of aspring member on the inner shaft member between the drive collar memberand the inner shaft stop member.

Additionally or alternatively, the connection mechanism may furtherinclude a spring member inserted on the inner shaft member between thedrive collar member and the inner shaft stop member.

Additionally or alternatively, an inner shaft stop member may bedisposed to slide on the inner shaft member and is movable along thelongitudinal direction. The inner shaft stop member is disposedproximally of the drive collar member. The inner shaft stop memberengages the at least one additional aperture to limit movement of theinner shaft member along the longitudinal axis following insertion ofthe spring member on the inner shaft member between the drive collarmember and the inner shaft stop member.

Additionally or alternatively, the spring member defines a proximal endand a distal end, and the drive collar member may further include aprojection extending proximally from the drive collar member and that isconfigured to engage within an aperture defined in the distal end of thespring member when the spring member is inserted on the inner shaftmember between the drive collar member and the inner shaft stop member.

Additionally or alternatively, the inner shaft stop member furtherincludes a projection that extends distally from the inner shaft stopmember and that is configured to engage within an aperture defined inthe proximal end of the spring member when the spring member is insertedon the inner shaft member between the drive collar member and the innershaft stop member.

Additionally or alternatively, the inner shaft member defines a firstcross-sectional area. The drive collar stop member defines a centralaperture having a second cross-sectional area exceeding the firstcross-sectional area. The second cross-sectional area defines an upperportion of the second cross-sectional area and a lower portion of thesecond cross-sectional area. The drive collar stop member defines atleast one projection projecting inwardly within the upper portion of thesecond cross-sectional area to reduce the upper portion of the secondcross-sectional area as compared to the lower portion of the secondcross-sectional area, and thereby the drive collar stop member retainsthe inner shaft member in the lower portion of the secondcross-sectional area as the drive collar stop member moves distallyalong the longitudinal direction.

Additionally or alternatively, when the drive collar stop member movesdistally along the longitudinal direction to the at least one distalaperture defined in the inner shaft member, the drive collar stop membershifts in a direction relative to the longitudinal axis to a positionwherein at least one projection engages with the at least one apertureand moves to a position within the at least one aperture to limitfurther longitudinal motion of the drive collar member in the directionof the proximal end of the inner shaft member.

Additionally or alternatively, the drive collar stop member defines atleast one portion having a weight density differing from at leastanother portion having another weight density, and the shift of thedrive collar stop member relative to the longitudinal axis is effectedby the difference in weight densities.

Additionally or alternatively, the inner shaft stop member defines anaperture and at least one projection that projects inwardly within theaperture, the aperture imparting a generally U-shaped configuration tothe inner shaft stop member. The at least one projection that projectsinwardly within the aperture effects the engaging of the at least oneadditional aperture disposed proximally of the drive collar member.

According to another aspect of the present disclosure, a method ofmanufacturing a connection mechanism for a surgical instrument isprovided. The method includes moving a drive collar stop memberlongitudinally along an inner shaft member, engaging the drive collarstop member in at least one aperture defined in the inner shaft memberto limit further longitudinal movement of the drive collar stop member,and moving a drive collar member longitudinally along the inner shaftmember until the drive collar stop member limits further longitudinalmovement of the drive collar member.

Additionally or alternatively, the method of manufacturing may furtherinclude inserting, in a compressed configuration, a spring member on theinner shaft member; and moving the spring member longitudinally alongthe inner shaft member to contact the drive collar member to limitfurther longitudinal movement of the spring member.

Additionally or alternatively, the method of manufacturing may furtherinclude moving an inner shaft stop member in a direction relative to thelongitudinal movement of the drive collar stop member along the innershaft member, and engaging the inner shaft stop member in at least oneadditional aperture defined in the inner shaft member to limitlongitudinal movement of the inner shaft stop member when the springmember contacts the inner shaft stop member upon extending from thecompressed configuration.

Additionally or alternatively, the step of engaging the drive collarstop member in at least one aperture defined in the inner shaft memberto limit further longitudinal movement of the drive collar stop memberincludes moving the drive collar stop member in a direction relative tothe longitudinal movement of the drive collar stop member to engage withthe at least one aperture defined in the inner shaft member to limitfurther longitudinal movement of the drive collar stop member.

Additionally or alternatively, the step of engaging the inner shaft stopmember in at least one aperture defined in the inner shaft member tolimit further longitudinal movement of the inner shaft stop memberincludes moving the inner shaft stop member in the direction of thelongitudinal movement of the drive collar member to engage with the atleast one aperture defined in the inner shaft member to limit furtherlongitudinal movement of the inner shaft member.

Additionally or alternatively, the method of manufacturing may furtherinclude engaging a projection extending proximally from the drive collarmember within an aperture defined in a distal end of the spring memberwhen the spring member is inserted on the inner shaft member between thedrive collar member and the inner shaft stop member.

Additionally or alternatively, the method of manufacturing may furtherinclude engaging a projection extending distally from the inner shaftstop member within an aperture defined in a proximal end of the springmember when the spring member is inserted on the inner shaft memberbetween the drive collar member and the inner shaft stop member.

Additionally or alternatively, the method of manufacturing may furtherinclude retaining the inner shaft member in a portion of an aperturedefined in the drive collar stop member as the drive collar stop membermoves distally along the longitudinal direction of the inner shaftmember.

Additionally or alternatively, the method of manufacturing may furtherinclude limiting further longitudinal motion of the drive collar memberin the direction of the proximal end of the inner shaft member byengaging the drive collar stop member with the at least one aperturedefined in the inner shaft member.

Additionally or alternatively, the engaging by the drive collar stopmember with the at least one aperture is effected by shifting the drivecollar stop member in a direction relative to the longitudinal movementof the drive collar stop member.

Additionally or alternatively, the drive collar stop member defines atleast one portion having a weight density differing from at leastanother portion having another weight density, and the shifting of thedrive collar stop member is effected by the difference in weightdensities.

Additionally or alternatively, the method of manufacturing may furtherinclude defining an aperture in the inner shaft stop member to impart agenerally U-shaped configuration to the inner shaft stop member, anddefining at least one projection projecting inwardly within the aperturedefined in the inner shaft stop member, wherein the engaging of the atleast one additional aperture disposed proximally of the drive collarmember by the inner shaft stop member is effected by engaging the atleast one projection projecting inwardly within the aperture defined inthe inner shaft stop member with the at least one additional aperturedisposed proximally of the drive collar member.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is a perspective view of an electrosurgical forceps according toan embodiment of the present disclosure including a housing, anelongated shaft, and an end effector;

FIG. 2A is an enlarged perspective view of the end effector of FIG. 1depicted with a pair of jaw members in an open configuration;

FIG. 2B is an enlarged perspective view of the end effector of FIG. 1depicted with the pair of jaw members in a closed configuration;

FIG. 3A is a perspective view of the end effector and elongated shaft ofFIG. 1 with parts separated;

FIG. 3B is an enlarged perspective view of a distal portion of theelectrosurgical forceps of FIG. 1 depicting a distal knife guide coupledto an inner shaft member;

FIG. 4 is a proximally-facing perspective view of a rotation knobdepicting a cavity for receiving the elongated shaft of FIG. 1;

FIG. 5 is a cross-sectional, perspective view of the end effectorassembled with the elongated shaft of FIG. 1;

FIG. 6 is a partial, perspective view of a distal portion of a jawactuation mechanism of the end effector of FIG. 1;

FIG. 7 is a partial, perspective view of distal portion of a knifeactuation mechanism of the end effector of FIG. 1;

FIG. 8 is a perspective view of a lower jaw member of the end effectorof FIG. 1 depicting a double flag at a proximal end thereof;

FIG. 9 is a cross-sectional, perspective view of the lower jaw member ofFIG. 8;

FIG. 10 is a schematic view of the nestled arrangement of the doubleflag of FIG. 8 with a double flag of an upper jaw member;

FIG. 11 is a schematic view of an alternative offset arrangement ofdouble flags of an alternate pair of jaw members;

FIG. 12 is a perspective view of a proximal portion of the instrument ofFIG. 1 with a portion of the housing removed revealing internalcomponents;

FIG. 13 is a partial, side view of a proximal portion of the jawactuation mechanism of FIG. 6 depicting a connection between the jawactuation mechanism and the jaw drive rod mechanism for impartinglongitudinal movement to the jaw drive rod;

FIG. 14A is a perspective view of a proximal portion of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 14B is a cross-sectional, top view of a knife collar of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 15A is a side view of the proximal portion of the instrument ofFIG. 12 depicting a movable handle in a separated position with respectto a stationary handle, which corresponds to the open configuration ofthe end effector depicted in FIG. 2A, and a knife trigger in a separatedconfiguration with respect to the stationary handle, which correspondsto an un-actuated or proximal configuration of a knife with respect tothe jaw members;

FIG. 15B is a side view of the proximal portion of the instrument ofFIG. 12 depicting the movable handle in an intermediate position withrespect to the stationary handle, which corresponds to a first closedconfiguration of the end effector wherein the jaw members encounter oneanother;

FIG. 15C is a side view of the proximal portion of the instrument ofFIG. 12 depicting the movable handle in an approximated configurationwith respect to the stationary handle, which corresponds to a secondclosed configuration of the end effector wherein the jaw members applyan appropriate pressure to generate a tissue seal;

FIG. 15D is a side view of the proximal portion of the instrument ofFIG. 12 depicting the knife trigger in an actuated configuration, whichcorresponds to an actuated or distal position of the knife with respectto the jaw members;

FIG. 16 is a partial, side view of a proximal portion of an alternateembodiment of a connection mechanism such as the jaw actuation mechanismof FIG. 13 depicting a connection between the jaw actuation mechanismand the jaw drive rod mechanism for imparting longitudinal movement tothe jaw drive rod in a manner to enhance the delivery of a requiredshaft force such as to the jaw members illustrated in FIG. 6;

FIG. 17 is a partial, side view of a proximal portion of the jawactuation mechanism of FIG. 16 depicting, without the movable handle, analternate embodiment of the connection between the jaw actuationmechanism and the jaw drive rod mechanism for imparting longitudinalmovement to the jaw drive rod;

FIG. 18 is a cross-sectional, side view of an inner shaft memberillustrating apertures in the inner shaft member and engagement of adrive collar and stop members on the inner shaft member;

FIG. 19A is a perspective view of the inner shaft stop member of FIGS.16-18;

FIG. 19B is another perspective view of the inner shaft stop member ofFIGS. 16-18;

FIG. 20A is a perspective view of the drive collar stop member of FIGS.16-18;

FIG. 20B is another perspective view of the drive collar stop member ofFIGS. 16-18;

FIG. 21A is a perspective detail view of the drive collar of FIGS.17-18;

FIG. 21B is another perspective detail view of the drive collar of FIGS.17-18;

FIG. 22 is a perspective view of the apertures in the inner shaft memberof FIG. 18;

FIG. 23 is a perspective view of the inner shaft member and drive collarand stop members on the inner shaft member;

FIG. 24A is an exploded view of the inner shaft member and drive collarand stop members with respect to the inner shaft member;

FIG. 24B is an alternate exploded view of the inner shaft member anddrive collar and stop members with respect to the inner shaft member asillustrated in FIG. 24A which includes directional arrows to illustratethe movement of the drive collar and stop members with respect to theapertures in the inner shaft member;

FIG. 24C is another exploded view of the inner shaft member and drivecollar and stop members with respect to the inner shaft member; and

FIG. 25 is a cutaway view of an electrosurgical forceps that includesthe inner shaft member and drive collar and stop members on the innershaft member of FIGS. 16-24C.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an embodiment of an electrosurgicalforceps 400 generally includes a housing 412 that supports variousactuators thereon for remotely controlling an end effector 414 throughan elongated shaft 416. Although this configuration is typicallyassociated with instruments for use in laparoscopic or endoscopicsurgical procedures, various aspects of the present disclosure may bepracticed with traditional open instruments and in connection withendoluminal procedures as well.

The housing 412 is constructed of a left housing half 412 a and a righthousing half 412 b. The left and right designation of the housing halves412 a, 412 b refer to the respective directions as perceived by anoperator using the forceps 400. The housing halves 412 a, 412 b may beconstructed of sturdy plastic, and may be joined to one another byadhesives, ultrasonic welding or other suitable assembly methods.

To mechanically control the end effector 414, the housing 412 supports astationary handle 420, a movable handle 422, a trigger 426 and arotation knob 428. The movable handle 422 is operable to move the endeffector 414 between an open configuration (FIG. 2A) wherein a pair ofopposed jaw members 430, 432 are disposed in spaced relation relative toone another, and a closed or clamping configuration (FIG. 2B) whereinthe jaw members 430, 432 are closer together. Approximation of themovable handle 422 with the stationary handle 420 serves to move the endeffector 414 to the closed configuration and separation of the movablehandle 422 from the stationary handle 420 serves to move the endeffector 414 to the open configuration. The trigger 426 is operable toextend and retract a knife blade 456 (see FIGS. 2A and 2B) through theend effector 414 when the end effector 414 is in the closedconfiguration. The rotation knob 428 serves to rotate the elongatedshaft 416 and the end effector 414 about a longitudinal axis A-Aextending through the forceps.

To electrically control the end effector 414, the housing 412 supports aswitch 436 thereon, which is operable by the user to initiate andterminate the delivery of electrosurgical energy to the end effector414. The switch 436 is in electrical communication with a source ofelectrosurgical energy such as electrosurgical generator 440 or abattery (not shown) supported within the housing 412. The generator 440may include devices such as the LIGASURE® Vessel Sealing Generator andthe Force Triad® Generator as sold by Covidien Energy-based Devices ofBoulder, Colo. A cable 442 extends between the housing 412 and thegenerator 440 and may include a connector (not shown) thereon such thatthe forceps 400 may be selectively coupled and decoupled electricallyfrom the generator 440.

Referring now to FIGS. 2A-3, the end effector 414 may be moved from theopen configuration (FIG. 2A) wherein tissue (not shown) is receivedbetween the jaw members 430, 432, and the closed configuration (FIG.2B), wherein the tissue is clamped and sealed. Upper jaw member 430 andlower jaw member 432 are mechanically coupled to the elongated shaft 416about a pivot pin 444. The upper and lower jaw members 430, 432 areelectrically coupled to cable 442, and thus to the generator 440 (e.g.,via a respective wire extending through the elongated shaft 416) toprovide an electrical pathway to a pair of electrically conductive,tissue-engaging sealing plates 448, 450 disposed on the lower and upperjaw members 432, 430, respectively. A pair of wire conduits 478 a and478 b may be provided to guide wires proximally from the end effector414. The wire conduits 478 a and 478 b may be constructed of a plastictube, and serve to protect wires from sharp edges that may form onsurrounding components. The sealing plate 448 of the lower jaw member432 opposes the sealing plate 450 of the upper jaw member 430, and, insome embodiments, the sealing plates 448 and 450 are electricallycoupled to opposite terminals, e.g., positive or active (+) and negativeor return (−) terminals associated with the generator 440. Thus, bipolarenergy may be provided through the sealing plates 448 and 450.Alternatively, the sealing plates 448 and 450 and/or the end effector414 may be configured for delivering monopolar energy to the tissue. Ina monopolar configuration, the one or both sealing plates 448 and 450deliver electrosurgical energy from an active terminal, e.g. (+), whilea return pad (not shown) is placed generally on a patient and provides areturn path to the opposite terminal, e.g. (−), of the generator 440.

The jaw members 430, 432 may be pivoted about the pivot pin 444 to movethe end effector 414 to the closed configuration of FIG. 2B wherein thesealing plates 448, 450 provide a pressure to tissue graspedtherebetween. In some embodiments, to provide an effective seal, apressure within a range between about 3 kg/cm2 to about 16 kg/cm2 and,desirably, within a working range of 7 kg/cm2 to 13 kg/cm2 is applied tothe tissue. Also, in the closed configuration, a separation or gapdistance “G” may be maintained between the sealing plates 448, 450 by anarray of stop members 454 (FIG. 2A) disposed on or adjacent the sealingplates 448, 450. The stop members 454 contact opposing surfaces on theopposing jaw member 430, 432 and prohibit further approximation of thesealing plates 448, 450. In some embodiments, to provide an effectivetissue seal, an appropriate gap distance of about 0.001 inches to about0.010 inches and, desirably, between about 0.002 and about 0.005 inchesmay be provided. In some embodiments, the stop members 454 areconstructed of an electrically non-conductive plastic or other materialmolded onto the jaw members 430, 432, e.g., by a process such asovermolding or injection molding. In other embodiments, the stop members454 are constructed of a heat-resistant ceramic deposited onto the jawmembers 430, 432.

Electrosurgical energy may be delivered to the tissue through theelectrically conductive seal plates 448, 450 to effect a tissue seal.Once a tissue seal is established, a knife blade 456 may be advancedthrough a knife channel 458 defined in one or both jaw members 430, 432to transect the sealed tissue. Knife blade 456 is depicted in FIG. 2A asextending from the elongated shaft 416 when the end effector 414 is inan open configuration. In some embodiments, a knife lockout is providedto prevent extension of the knife blade 456 into the knife channel 458when the end effector 414 is in the open configuration, thus preventingaccidental or premature transection of tissue and avoiding safetyconcerns.

Referring now to FIG. 3A, the elongated shaft 416 includes variouslongitudinal components that operatively couple the end effector 414 tothe various actuators supported by the housing 412 (FIG. 1). An outershaft member 460 defines an exterior surface of the elongated shaft 416and supports movement of other components therethrough as describedbelow. The outer shaft member 460 may be constructed from a flat stockpiece of metal. In constructing the outer shaft member 460, a stamping,punching or similar metal-working process may be employed to initiallygenerate a flat blank that includes an appropriate outer profile and anyinterior openings or features. Thereafter, the necessary bends andcurves may be formed by bending the flat blank with a press brake, orother suitable metal-working equipment. The outer shaft member 460 maybe formed by folding the flat blank into a generally circular profile(or generally rectangular profile) such that two opposing longitudinaledges of the flat blank meet at a longitudinal seam (not explicitlyshown). Although the longitudinal seam does not necessarily requirejoining by a mechanical interlock or any other suitable process, theseam may, in some embodiments, be joined by laser welding (or othersuitable process) to form a continuous circular or other geometric(e.g., rectangular) profile. The seam may be generally straight, oralternatively, a box joint, a dovetail joint, or any other suitableinterface known in the metal-working arts.

The outer shaft member 460 defines a clevis 464 at a distal end thereoffor receiving the jaw members 430 and 432. Opposing vertical sidewalls464 a and 464 b of the outer shaft member 460 include respective bores466 a, 466 b extending therethrough to frictionally support the pivotpin 444 and maintain an orientation of the pivot pin 444 with respect tothe outer shaft member 460. Alternatively or additionally, the pivot pin444 may be fastened to the outer shaft member 460 by a laser orheat-based welding, adhesives, chemical bonding, or other suitablemanufacturing processes.

At a proximal portion of the outer shaft member 460, various featuresare provided that serve to couple the outer shaft member 460 to variouselements of the housing 412. More specifically, the proximal portion ofthe outer shaft member 460 includes, in order from distal to proximal, aseries of tabs 486 extending therefrom, a washer 499 extending aroundouter shaft member 460, a pair of opposing longitudinal slots 468 a, 468b defined therethrough and provided to allow longitudinal translation ofa dowel pin 493 therethrough, and a longitudinal slot 469 extendingdistally from a proximal end thereof to couple the outer shaft member460 to the rotation knob 428. The connection established between theouter shaft member 460 and the rotation knob 428 is described below withreference to FIG. 4. As shown in FIGS. 15A-15D, the series of tabs 486and the washer 499 serve to aid in securing the proximal portion of theouter shaft member 460 within the housing 412.

The pivot pin 444 extends through a proximal portion of each of the jawmembers 430, 432 to pivotally support the jaw members 430, 432 at thedistal end of the outer shaft member 460. With reference to FIG. 8, aproximal portion of each of the jaw members 430, 432 is configured as a“double flag.” The double flag configuration refers to the two laterallyspaced parallel flanges or “flags” 430 a, 430 b and 432 a, 432 brespectively, extending proximally from a distal portion of the jawmembers 430 and 432. A lateral cam slot 430 c and a lateral pivot bore430 d extend through each of the flags 430 a, 430 b of the upper jawmember 430. Similarly, a lateral cam slot 432 c and a lateral pivot bore432 d extend through each of the flags 432 a, 432 b of the lower jawmember 432. The pivot bores 430 d, 432 d receive the pivot pin 444 in aslip-fit relation that permits the jaw members 430, 432 to pivot aboutthe pivot pin 444 to move the end effector 414 between the open andclosed configurations (FIGS. 2A and 2B, respectively).

An inner shaft member 480 is received within the outer shaft member 460and is configured for longitudinal motion with respect to the outershaft member 460. A distal knife guide 486 includes sidewalls 482 a, 482b and a proximal key slot 487 that supports a key member 494therethrough. During assembly of electrosurgical forceps 400, the distalknife guide 486 is slid proximally within a distal end of the innershaft member 480, such that the inner shaft member 480 surrounds aportion of the distal knife guide 486, and opposing lateral sides of thekey member 494 align with and fit within opposing longitudinal key slots495 a, 495 b defined through the inner shaft member 480 to couple theknife guide 486 to the inner shaft member 480 (FIG. 3B). The inner shaftmember 480 includes a pair of opposing longitudinal slots 472 a, 472 bextending proximally from a distal end of the inner shaft member 480along a portion of the inner shaft member 480 between the opposinglongitudinal key slots 495 a, 495 b. The longitudinal slots 472 a, 472 ballow the distal end of the inner shaft member 480 to aid in sliding ofthe distal knife guide 486 proximally within the inner shaft member 480.Once the key member 494 is aligned with and fit within the longitudinalkey slots 495 a, 495 b, the key member 494 effectively couples thedistal knife guide 486 to the inner shaft member 480, as depicted byFIG. 3B.

The sidewalls 482 a, 482 b define a longitudinal slot 483 through thedistal knife guide 486 that provides lateral support to the knife 402.The knife 402 is substantially surrounded at a distal end thereof by thedistal knife guide 486 on four lateral sides and the sidewalls 482 a,482 b of the distal knife guide 486 constrain side-to-side lateralmotion of the knife 402. Thus, the distal knife guide 486 serves to urgethe knife 402 into a central position within the elongated shaft 416,thereby ensuring proper alignment of the knife 402 as the knife 402reciprocates within knife channel 458 (FIG. 2A). The distal knife guide486 includes features for operatively coupling the inner shaft member480 to the end effector 414. A proximal portion 488 of the inner shaftmember 480 is configured for receipt within the housing 412 (FIG. 1),and includes features for operatively coupling the inner shaft member480 to the actuators supported thereon, e.g. the movable handle 422.

The distal knife guide 486 includes a through bore 490 extending throughthe sidewalls 482 a, 482 b for receiving the cam pin 492. Distally ofthe through bore 490, a longitudinal slot 496 is defined through thesidewalls 482 a, 482 b. The longitudinal slot 496 provides clearance forthe pivot pin 444, and thus, permits longitudinal reciprocation of theinner shaft member 480 independent of the pivot pin 444.

The proximal portion 488 of the inner shaft member 480 includes, inorder from distal to proximal, a pair of opposing longitudinal knifeslots 488 a, 488 b extending therethrough, a pair of opposing distallocking slots 481 a, 481 b extending therethrough, a pair of opposingproximal locking slots 471 a, 471 b extending therethrough, and aproximal end 491 configured to engage a suitable mechanical interfacewithin the housing 412 to aid in proper support of the inner shaftmember 480 within the housing 412 (see FIGS. 12 and 15A-15D).

The knife 402 is a generally flat, metal component defining a profilethat may be constructed by a stamping process. The knife 402 supportsthe sharpened knife blade 456 at a distal-most end thereof. The sharpedge of the knife blade 456 may be applied to the distal end of theknife 402 subsequent to the stamping process that forms the profile. Forexample, various manufacturing techniques may be employed such asgrinding, coining, electrochemical etching, electropolishing, or othersuitable manufacturing processes, for forming sharpened edges. Alongitudinal slot 406 is defined within the knife 402 to provideclearance for the pivot pin 444, the cam pin 492, and the key member494. A proximal through bore 408 a extends through a proximal portion408 of the knife 402 and provides a mechanism for operatively couplingthe knife 402 to the trigger 426 via the dowel pin 493. The connectionbetween the knife 402 and the trigger 426 is described in detail belowwith reference to FIGS. 12, 13, 14A, and 14B.

Referring now to FIG. 4, the rotation knob 428 includes a passageway 429defined therethrough for receiving the outer shaft member 460. Thepassageway 429 has a generally circular profile corresponding to thecircular profile of the outer shaft member 460. The passageway 429includes a longitudinal keying member 414 that is configured to alignwith and be seated within longitudinal slot 469 (FIG. 3A) of the outershaft member 460. The keying member 414 projects laterally inward alongthe length of passageway 429 such that the insertion of the proximal endof the outer shaft member 460 into the passageway 429 of the rotationknob 428 operatively couples the outer shaft member 460 to the rotationknob 428 and, thus, permits longitudinal motion of the inner shaftmember 480 therethrough.

In one embodiment, a cable clearance passageway (not shown) is definedthrough rotation knob 428 to permit passage of electrical cables orwires that electrically couple the sealing plates 448, 450 to theelectrosurgical generator 440 (FIG. 1). Rotational motion imparted tothe rotation knob 428 may thus impart rotational motion to each of thecomponents of the elongated shaft 416, and to the end effector 414,which is coupled thereto.

As shown in FIG. 13, the rotation knob 428 is seated within an interiorcompartment 434 of the housing 412 and, as shown in FIG. 1, extendslaterally outward from opposing sides of the housing 412 (only shownextending laterally outward from housing half 412 b). The interiorcompartment 434 defines distal and proximal passageways 434 a and 434 bthat permit the passage of the components of the elongated shaft 416therethrough. The rotational motion of the rotation knob 428 may belimited by a stop boss 430 projecting distally from the rotation knob428 (FIG. 4). The stop boss 430 is positioned to engage the distalpassage 434 a of the compartment 434 to restrict rotational motion ofthe rotation knob 428. For example, in some embodiments, the stop boss430 may engage the distal passage 434 a to restrict rotational motion ofthe rotation knob 428 to 180 degrees in either direction.

Referring now to FIG. 5, the end effector 414 is coupled to the distalend of the elongated shaft 416 by the pivot pin 444. The pivot pin 444is coupled to the sidewalls 464 a and 464 b of the clevis 464 defined atthe distal end of the outer shaft member 460. Thus, the pivot pin 444represents a longitudinally stationary reference for the longitudinalmovements of inner shaft member 480 and the knife 402. Laterally inwardof the sidewalls 464 a, 464 b, the pivot pin 444 extends through theflags 432 a, 432 b of the lower jaw member 432, the flags 430 a and 430b of the upper jaw member 430, the sidewalls 482 a, 482 b of the knifeguide 486, and the knife 402. The jaw members 430, 432 are free to pivotabout the pivot pin 444, and the inner shaft member 480 and the knife402 are free to translate longitudinally around the pivot pin 444.

Referring now to FIG. 6, the end effector 414 is shown in the openconfiguration. Since the knife guide 486 is coupled to the cam pin 492,when the inner shaft member 480 is in the distal position, the cam pin492 is located in a distal position in cam slots 430 c and 432 c definedthrough the flags 430 a, 430 b, 432 a, 432 b of the jaw members 430,432, respectively.

The inner shaft member 480 may be drawn proximally relative to the pivotpin 444 to move the end effector 414 to the closed configuration (seeFIG. 2B). Since the longitudinal position of the pivot pin 444 is fixed(by the outer shaft member 460, which is removed from view in FIG. 6 forclarity), and since the cam slots 430 c, 432 c are obliquely arrangedwith respect to the longitudinal axis A-A, proximal retraction of thecam pin 492 through the cam slots 430 c, 432 c induces the jaw members430, 432 to pivot toward one another about the pivot pin 444.Conversely, when the end effector 414 is in the closed configuration,longitudinal translation of the inner shaft member 480 in a distaldirection induces the jaw members 430, 432 to pivot away from oneanother toward the open configuration.

Referring now to FIG. 7, the longitudinal slot 406 in the knife 402extends around both the pivot pin 444 and the cam pin 492, and thus thepins 444, 492 do not interfere with the reciprocal motion of the knife402. The pivot pin 444 and cam pin 492 extend through the slot 406 insuch a manner as to guide longitudinal motion of the knife 402 as wellas constrain vertical motion of the knife 402. The blade 456 at thedistal-most end of the knife 402 is centrally aligned by the knife guide486, as discussed hereinabove. Properly aligned, the blade 456 readilyenters the knife channel 458 defined in the jaw members 430, 432.

Referring now to FIGS. 8 and 9, the lower jaw member 432 is constructedof three major components. These components include a double-flag jawinsert 440, an insulator 442 and the sealing plate 448. The flags 432 a,432 b of the jaw member 432 define a proximal portion of the double-flagjaw insert 440, and a generally u-shaped channel 444 extends distally tosupport the tissue engaging portion of the jaw member 432. Thedouble-flag jaw insert 440 includes various planar surfaces, and may beconstructed as a sheet metal component formed by a stamping process. Insuch a stamping process, the cam slots 432 c and pivot holes 432 d maybe punched into a flat blank, and subsequently the blank may be bent toform the flags 432 a, 432 b and the u-shaped channel 444.

The insulator 442 may be constructed of an electrically insulativeplastic such as a polyphthalamide (PPA) (e.g., Amodel®), polycarbonate(PC), acrylonitrile butadiene styrene (ABS), a blend of PC and ABS,nylon, ceramic, etc. The electrically insulative plastic may beovermolded onto the jaw insert 440 in a single-shot injection moldingprocess such that sealing plate 448 is overmolded to the jaw insert 440.Additionally or alternatively, the electrically insulative plastic maybe mechanically coupled to the jaw insert 440, e.g., pressed, snapped,glued, etc. Various features may be molded into the insulator 442 thatfacilitate the attachment of the sealing plate 448 to the insert 440.For example, tabs may be provided that permit a snap-fit attachment ofthe sealing plate 448, or ridges may formed that permit ultrasonicwelding of the sealing plate 448 onto the insulator 442. The sealingplate 448 may be constructed of an electrically conductive metal, andmay be stamped from a flat sheet stock.

Referring now to FIG. 10, the flags 430 a, 430 b of the upper jaw member430 are depicted schematically in a nestled configuration with respectto the flags 432 a, 432 b of the lower jaw member 432. The proximalportion of the upper jaw member 430 is narrower than the proximalportion of the lower jaw member 432, and thus, a lateral spacing “S”between the flags 432 a, 432 b is sufficient to permit the flags 430 aand 430 b to be positioned therebetween. A pivot axis “P0” extendsthrough an overlapping portion of the flags 430 a, 432 a, and 430 b, 432a such that the upper and lower jaw members 430, 432 may pivot about thecommon axis “P0.” In the nestled configuration, the proximal portions ofthe upper and lower jaw members 430, 432 also share a common centerline“CL-1” that is transverse with respect to the pivot axis “P0.”

An alternative to the nestled configuration illustrated in FIG. 10 isthe offset configuration illustrated schematically in FIG. 11. Aproximal portion of double-flag upper jaw member 450 includes flags 450a and 450 b. A proximal portion of a double-flag lower jaw member 452includes flags 452 a and 452 b and exhibits a width that is identical toa width of the proximal portion of the upper jaw member 450. To providean overlapping portion of the flags 450 a, 452 a and 450 b, 452 b suchthat the jaw members 450, 452 may pivot about the common axis “P0,” oneflag 450 a of the upper jaw member 450 is positioned on a laterallyexterior side of the corresponding flag 452 a of the lower jaw member452, and the other flag 450 b of the upper jaw member 450 is positionedon a laterally interior side of the corresponding flag 452 b of thelower jaw member 452. In the offset configuration, a centerline “CL-2”of the proximal portion of the upper jaw member 450 is laterally offsetwith respect to a centerline “CL-3” of the lower jaw member 452.

Referring now to FIG. 12, the connection of the movable handle 422 andthe knife trigger 426 to the longitudinally movable components of theelongated shaft 416 is described. The movable handle 422 may bemanipulated to impart longitudinal motion to the inner shaft member 480,and the knife trigger 426 may be manipulated to impart longitudinalmotion to the knife 402. As discussed above, longitudinal motion of theinner shaft member 480 serves to move the end effector 414 between theopen configuration of FIG. 2A and the closed configuration of FIG. 2B,and longitudinal motion of the knife 402 serves to move knife blade 456through knife channel 458 (FIG. 2A).

The movable handle 422 is operatively coupled to the inner shaft member480 by a connection mechanism 476 (FIG. 12). The connection mechanism476 includes a clevis 478 defined at an upper end of the movable handle422. The clevis 478 is pivotally supported on the left housing half 412b by a pivot boss 479. A second complementary pivot boss (not shown) isprovided on the right housing half 412 a to support the clevis 478. Eachof two upper flanges 478 a and 478 b of the clevis 478 extend upwardlyabout opposing sides of a drive collar 484 supported on the inner shaftmember 480 and include rounded drive surfaces 497 a and 497 b thereon.Drive surface 497 a engages a proximal-facing surface of a distal lockcollar 484 a and drive surface 497 b engages a distal facing surface ofa proximal rim 484 b of the drive collar 484 (FIG. 13). The distal lockcollar 484 a engages the opposing distal locking slots 481 a, 481 b(FIG. 3A) extending through the proximal portion 488 of the inner shaftmember 480 to lock-fit the distal lock collar 484 a to the inner shaftmember 480. Thus, the distal lock collar 484 a is prevented fromlongitudinal motion relative to the inner shaft member 480. Drivesurface 497 a is arranged along the longitudinal axis A-A such thatpivotal motions of the movable handle 422 about the pivot bosses 479induce corresponding longitudinal motion of the drive collar 484 alongthe longitudinal axis A-A in the proximal direction. Drive surface 497 bis arranged along the longitudinal axis A-A such that pivotal motions ofthe movable handle 422 about the pivot bosses 479 induce correspondinglongitudinal motion of the distal lock collar 484 a along thelongitudinal axis A-A in the distal direction.

Referring now to FIG. 13, proximal longitudinal motion may be impartedto the inner shaft member 480 by pushing the proximal rim 484 b of thedrive collar 484 proximally with the movable handle 422 (FIG. 12) asindicated by arrow D4. The proximal rim 484 b engages a spring 489 thatis constrained between the proximal rim 484 b and a proximal lock collar415. The proximal lock collar 415 engages the opposing proximal lockingslots 471 a, 471 b (FIG. 3A) extending through the proximal portion 488of the inner shaft member 480 to lock-fit the proximal lock collar 415to the inner shaft member 480. Thus, the proximal lock collar 415 isprevented from longitudinal motion relative to the inner shaft member480 and serves as a proximal stop against which spring 489 compresses.

Distal longitudinal motion is imparted to the inner shaft member 480 bypushing the distal lock collar 484 a distally with drive surface 497 aof movable handle 422 as indicated by arrow D3 (FIG. 13). Distallongitudinal motion of the distal lock collar 484 a induces acorresponding distal motion of the inner shaft member 480 by virtue ofthe lock-fit coupling of the distal lock collar 484 a to the opposingproximal locking slots 471 a, 471 b extending through the proximalportion 488 of the inner shaft member 480 (FIG. 3A).

Proximal longitudinal motion of the inner shaft member 480 draws the campin 492 proximally to pivot the jaw members 430, 432 toward one anotherto move the end effector 414 to the closed configuration as describedabove with reference to FIG. 6. Once the jaw members 430 and 432 areclosed, the inner shaft member 480 essentially bottoms out (i.e.,further proximal movement of the inner shaft member 480 is prohibitedsince the jaw members 430, 432 contact one another). Further proximalmovement of the movable handle 422 (FIG. 12), however, will continue tomove the drive collar 484 proximally. This continued proximal movementof the drive collar 484 further compresses the spring 489 to impartadditional force to the inner shaft member 480, which results inadditional closure force applied to tissue grasped between the jawmembers 430, 432 (see FIG. 2B). The spring 489 also serves to bias themovable handle 422 to an open configuration such that the movable handle422 is separated from the stationary handle 420.

Referring again to FIG. 12, the trigger 426 is pivotally supported inthe housing 412 about a pivot boss 403 protruding from the trigger 426.The trigger 426 is operatively coupled to the knife 402 by a knifeconnection mechanism 404 such that pivotal motion of the trigger 426induces longitudinal motion of the knife 402. The knife connectionmechanism 404 includes upper flanges 426 a, 426 b of the trigger 426 anda knife collar 410.

Referring now to FIGS. 13, 14A, and 14B, the knife collar 410 includes acap member 411 coupled thereto and a pair of integrally formed pinbosses 439 a, 439 b extending from opposing sides thereof. The knifecollar 410 may include indentations or catches defined therein (notshown) that receive corresponding snap-in features (e.g., arms) of thecap member 411. The cap 411 may thus be assembled to the knife collar410 such that the cap 411 and the knife collar 410 translate together.As shown by FIG. 14B, the coupling of the knife collar 410 to the cap411 forms an interior circular channel 413 to capture the dowel pin 493therein such that the dowel pin 493 is supported on opposing endsbetween the knife collar 410 and the cap 411. The dowel pin 493 extendsthrough the proximal through bore 408 a extending through a proximalportion 408 of the knife 402 (FIG. 3A) to operably couple the knife 402to the knife collar 410. Upon longitudinal motion of the inner shaftmember 480, dowel pin 493 translates longitudinally within knife slots488 a, 488 b, respectively, of the inner shaft member 480 such that thelongitudinal motion of inner shaft member 480 is unimpeded by dowel pin493. Upon rotation of the elongated shaft 416 and end effector 414 aboutthe longitudinal axis A-A via the rotation knob 428 (FIG. 1), dowel pin493 freely rotates within the interior circular channel 413 such thatthe outer and inner shaft members 460 and 480 (removed from view in FIG.14B for clarity), the knife 402, and the dowel pin 493 rotate within theknife collar 410 about the longitudinal axis A-A. In this way, the knifecollar 410 serves as a stationary reference for the rotational movementof the outer shaft member 460, the inner shaft member 480, the knife402, and the dowel pin 493.

Referring again to FIG. 12, the upper flanges 426 a, 426 b of thetrigger 426 include respective slots 427 a, 427 b defined therethroughthat are configured to receive the pin bosses 439 a, 439 b,respectively, of the knife collar 410 such that pivotal motion of thetrigger 426 induces longitudinal motion of the knife collar 410 and,thus, the knife 402 by virtue of the coupling of knife 402 to the knifecollar 410 via the dowel pin 493 extending through the through bore 408a. During longitudinal motion of the knife collar 410, dowel pin 493translates longitudinally within the opposing slots 468 a, 468 b of theouter shaft member 460 and the slots 488 a, 488 b of the inner shaftmember 480.

Referring now to FIGS. 13 and 14A, when the trigger 426 is moved toinduce motion of the knife collar 410 in order to translate the blade456 through the knife channel 458, the knife collar 410 translates alongthe outer shaft member 460 in the direction of arrow A9 to abut a spring419 such that spring 419 compresses against a distal portion 421 of theinterior of the housing 412 (FIG. 12). The spring 419 biases the knifecollar 410 in a proximal direction to a proximal position along theouter shaft member 460.

Referring now to FIGS. 15A, 15B, 15C and 15D, a sequence of motions maybe initiated by moving the movable handle 422 to induce motion of thejaw drive mechanism in order to close the jaws 430, 432, and by movingthe trigger 426 to induce motion of the knife collar 410 in order totranslate the blade 456 through the knife channel 458. Initially, boththe moveable handle 422 and the knife trigger 426 are in a distal orun-actuated position as depicted in FIG. 15A. This arrangement of themoveable handle 422 and trigger 426 sustains the end effector 414 in theopen configuration (FIG. 2A) wherein the jaw members 430, 432 aresubstantially spaced from one another, and the knife blade 456 is in aretracted or proximal position with respect to the jaw members 430, 432.The initial distal position of the trigger 422 is actively maintained bythe influence of the spring 419 on the knife collar 410. The distalposition of the moveable handle 422, however, is only passivelymaintained, e.g., by internal friction within the jaw actuationmechanism. When both the moveable handle 422 and the knife trigger 426are in the distal, un-actuated position, pivotal motion of the knifetrigger 426 in a proximal direction, i.e., toward the stationary handle420, is prohibited by interference between the trigger 426 and moveablehandle 422. This interference prohibits advancement of the knife bladethrough the knife channel 458 when the end effector 414 is in the openconfiguration.

The movable handle 422 may be moved from the distal position of FIG. 15Ato the intermediate position depicted in FIG. 15B to move the jawmembers 430, 432 to the closed configuration (FIG. 2B). As the movablehandle 422 pivots about the pivot boss 479 in the direction of arrow M1(FIG. 15B), the drive surface 497 b of the movable handle 422 engagesthe proximal rim 484 b of the drive collar 484. The drive collar 484 andthe spring 489 are both driven proximally against the proximal lockcollar 415 and, thus, the inner shaft member 480 is driven proximally inthe direction of arrow M2 (FIG. 15B). As discussed above with referenceto FIG. 6, proximal movement of the inner shaft member 480 serves todraw the cam pin 492 proximally though the cam slots 430 c, 432 c of thejaw members 430, 432, respectively, and thus pivot the jaw members 430,432 toward one another. As the jaw members 430, 432 engage one anotherand no further pivotal movement of the jaw members 430, 432 may beachieved, the jaw actuation mechanism “bottoms out” and further proximalmovement of the cam pin 492 and the inner shaft member 480 is prevented.

The movable handle 422 may be moved from the intermediate position ofFIG. 15B to the actuated or proximal position of FIG. 15C to increasethe pressure applied by the jaw members 430, 432. As the movable handle422 pivots further about the pivot boss 479 in the direction of arrow M3(FIG. 15C), the drive surface 497 b presses the proximal rim 484 b ofthe drive collar 484 further distally against the spring 489 in thedirection of arrow M4 (FIG. 15C). The spring 489 is compressed againstthe proximal lock collar 415, and a tensile force is transmitted throughthe inner shaft member 480 to the jaw members 430, 432. The tensileforce supplied by the spring 489 ensures that the jaw members 430, 432apply an appropriate pressure to effect a tissue seal. When the movablehandle 422 is in the actuated or proximal position, electrosurgicalenergy may be selectively supplied to the end effector 414 to generate atissue seal.

When the movable handle 422 is in the actuated or proximal position, at-shaped latch 422 a extending proximally from an upper portion of themoveable handle 422 is received in a railway 420 a supported within thestationary handle 420. The railway 420 a serves to temporarily lock themovable handle 422 in the proximal position against the bias of thespring 489. Thus, the railway 420 a permits the maintenance of pressureat the end effector 414 without actively maintaining pressure on themovable handle 422. The flange 422 a may be released from the railway420 a by pivoting the movable handle 422 proximally and releasing themovable handle 422 to move under the influence of the spring 489.Operation of the railway 420 a is described in greater detail in U.S.patent application Ser. No. 11/595,194 to Hixson et al., now U.S. Pat.No. 7,766,910. In some embodiments (not shown), the latch 422 a and therailway 420 a may be eliminated to provide an instrument without thetemporary locking capability provided by these features.

When the movable handle 422 is in the actuated or proximal position, theknife trigger 426 may be selectively moved from the distal position ofFIG. 15C to the proximal position of FIG. 15D to advance the knife blade456 distally through knife channel 458. The knife trigger 426 may bepivoted in the direction of arrow M5 (FIG. 15D), about pivot boss 403 toadvance the flange 426 b of the knife trigger 426 distally in thedirection of arrow M6 such that the pin boss 439 b translates withinslot 427 b from the position shown in FIGS. 15A-15C to the positionshown in FIG. 15D. Although not explicitly shown in FIGS. 15A-15D, pinboss 439 a translates within slot 427 a in the same manner as describedabove with respect to pin boss 439 b and slot 427 b. Movement of flanges426 a, 426 b draws the knife collar 410 distally, which induces distallongitudinal motion of the knife 402 by virtue of the coupling of knife402 to the knife collar 410 via the dowel pin 493 extending through thethrough bore 408 a, as described above with reference to FIGS. 3A and14B.

An alternate embodiment of a connection mechanism for a surgicalinstrument, e.g., an alternate embodiment of an actuation mechanism suchas the connection mechanism 476 described above with respect to FIGS.12-15D is now described with respect to FIGS. 16-25. Wherever possible,like component numbering is utilized to identify like components.

It should be noted that although this description relates to aconnection mechanism for a surgical instrument that includes an endeffector assembly with jaw members such as surgical instrument 400described above with respect to FIGS. 1-15D, the connection mechanismdescribed herein may also be applied to other types of surgicalinstrumentation.

More particularly, FIG. 16 is a view of a proximal portion of analternate embodiment of a connection mechanism for a surgical instrument(e.g., for surgical instrument 400 and elongated shaft member 416described above with respect to FIGS. 1-15D) such as the jaw actuationmechanism of FIG. 13. FIG. 16 depicts connection mechanism 4760 betweenthe jaw actuation mechanism and the jaw drive rod mechanism forimparting longitudinal movement to the jaw drive rod in a manner toenhance the delivery of a required shaft force such as to the pair ofopposed jaw members 430, 432 illustrated in FIG. 6 via the elongatedshaft 416 illustrated, for example, in FIGS. 1, 2A and 2B.

Referring also to FIG. 17, the clevis 478 of movable handle 422illustrated in FIG. 16 covers a portion of the connection mechanism4760. As best illustrated in FIG. 17, where the clevis 478 of movablehandle 422 is not illustrated, connection mechanism 4760 includes aninner shaft member 4800 that is configured to extend at least partiallythrough an elongated shaft member such as elongated shaft member 416 ofsurgical instrument 400. Inner shaft member 4800 defines proximal end4910 and a distal end (not explicitly shown but located in the directionof arrow 4912 in FIG. 22 and similarly to slots 472 a and 472 b in innershaft 480 in FIG. 3A). The inner shaft member 4800 is selectivelymovable in a longitudinal direction, such as defined by axis “A”-“A” inFIG. 1, with respect to the elongated shaft 416. As described in moredetail below, connection mechanism 4760 also includes a drive collarmember 4840, a drive collar stop member 4841 and an inner shaft stopmember 4150.

As best illustrated in FIGS. 18, 22, 24A, 24B and 24C, inner shaftmember 4800 includes at least one aperture, e.g., at least distallocking slot 4811 or additionally, as shown, at least distal lockingslot 4812, that is defined in the inner shaft member 4800. The distallocking slots 4811, 4812 extend partially along the longitudinaldirection (axis “A”-“A”) of the inner shaft member 4800 and are disposeddistally from the proximal end 4910.

The inner shaft member 4800 is configured such that the inner shaftmember 4800 enables drive collar member 4840 to be disposed to slide onthe inner shaft member 4800 and movable along the longitudinal direction(axis “A”-“A”) of the inner shaft member 4800. In one embodiment, thedrive collar member 4840 is reciprocally movable along the longitudinaldirection (axis “A”-“A”) of the inner shaft member 4800.

The distal locking slots 4811, 4812 may be configured in an L-shape, oras shown in FIGS. 18, 22, 24A, 24B and 24C in a T-shape having proximalsections 4811 a, 4812 a and distal sections 4811 b, 4812 b configuredsuch that the open area of the proximal sections 4811 a, 4812 a isgreater than the open area of the distal sections 4811 b, 4812 b. Such aconfiguration of the locking slots 4811, 4812 enables a drive collarstop member 4841 to be disposed to slide on the inner shaft member 4800such that the drive collar stop member 4841 moves first distally in adirection along the longitudinal axis “A”-“A” defined by the inner shaftmember 4800 to approach the distal locking slots 4811, 4812 (see arrowE1 in FIG. 24B). Once slid proximate to locking slots 4811, 4812, thedrive collar stop member 4841 moves in a direction relative to thelongitudinal direction defined by axis “A”-“A” by shifting or droppinginto engagement (see arrow E2 in FIG. 24B) first with the proximalsections 4811 a, 4812 a and then with the distal sections 4811 b, 4812 b(see arrow E3 in FIG. 24B) to limit further longitudinal motion of thedrive collar member 4840 in the direction of the proximal end 4912 ofthe inner shaft member 4800. In one embodiment, the drive collar stopmember 4841 is reciprocally movable or slidable along the longitudinalaxis “A”-“A” defined by the inner shaft member 4800.

As best illustrated in FIG. 23, the inner shaft member 4800, having, forexample, a circular cross-sectional configuration with a diameter D,therefore defines a first cross-sectional area B1. As best illustratedin FIGS. 20A and 20B, the drive collar stop member 4841 defines acentral aperture 4842 having a second cross-sectional area B2. Thesecond cross-sectional area B2 exceeds the first cross-sectional area B1of the inner shaft member 4800 so as to define an upper portion 4842′ ofthe second cross-sectional area B2 and a lower portion 4842″ of thesecond cross-sectional area B2. The reduced area of the firstcross-sectional area B1 results from the fact that, within the upperportion 4842′, the drive collar stop member 4841 defines at least oneprojection, e.g., as illustrated two projections 4843′, 4843″, thatproject inwardly to reduce the upper portion 4842′ of the secondcross-sectional area B2 as compared to the lower portion 4842″.

Thereby, as best illustrated in FIGS. 20A, 20B, 24A, 24B and 24C, thedrive collar stop member 4841 retains the inner shaft member 4800 in thelower portion 4842″ of the second cross-sectional area B2 as the drivecollar stop member 4841 moves distally along the longitudinal directionbetween the proximal end 4910 of the inner shaft member 4800 and thedistal locking slots 4811, 4812.

As described above with respect to FIGS. 18, 22, 24A, 24B and 24C, thedrive collar stop member 4841 moves distally along the longitudinaldirection (see FIG. 24B, arrow E1) to the distal locking slots 4811,4812. When slid proximate to locking slots 4811, 4812, the drive collarstop member 4841 drops or shifts (see FIG. 24B, arrow E2) to a positionwherein the projections 4843′, 4843″ engage first with the proximalsections 4811 a, 4812 a and then with the distal sections 4811 b, 4812 b(see FIG. 24B, arrow E3). Once the projections 4843′, 4843″ movedistally within the distal sections 4811 b, 4812 b along the entirelength of the distal sections 4811 b, 4812 b, drive collar stop member4841 then limits further longitudinal motion of the drive collar member4840 in the direction of the proximal end 4912 of the inner shaft member4800.

In one embodiment, as best illustrated in FIGS. 20A, 20B, 23 and 24A,24B and 24C, the drive collar stop member 4841 defines at least oneportion 4841′ having a weight density differing from at least anotherportion 4841″ having another weight density. The shift of the drivecollar stop member 4841 is effected by the difference in weightdensities. More particularly, in the exemplary embodiment describedherein, portion 4841′ defines an upper portion of the drive collar stopmember 4841 and portion 4841″ defines a lower portion of the drivecollar stop member 4841. The upper portion 4841′ defines, for example,three apertures 4845 a, 4845 b and 4845 c that are disposed,respectively, as arcuate segments forming a generally concentricconfiguration around the central aperture 4842.

In contrast, the lower portion 4841″ is a solid member such that theweight density exceeds the weight density of the upper portion 4841′that defines the apertures 4845 a, 4845 b, 4845 c. In this manner, asdescribed above, the difference in weight densities effects the movementor shifting of the drive collar member 4841 in a direction relative tothe longitudinal axis “A”-“A” defined by the inner shaft member 4800(see FIG. 24B, arrow E2) to become engaged first with the proximalsections 4811 a, 4812 a and then with the distal sections 4811 b, 4812 bto limit further longitudinal motion of the drive collar member 4840 inthe direction of the proximal end 4912 of the inner shaft member 4800(see FIG. 25, arrows E1 and E3). As can be appreciated, this facilitatesalignment and assembly during manufacturing.

As best illustrated in FIGS. 21A, 21B, 24A, 24B and 24C, drive collarmember 4840 may be configured as a cylindrical member 4844 defining acentral aperture 4844′ having a diameter D′ that is greater thandiameter D of inner shaft member 4800 (see FIG. 23) so as to enable thedrive collar 4840 to be mounted on the inner shaft member 4800 andreciprocally slide and move along the inner shaft member 4800.

Referring again to FIGS. 18, 22, 24A, 24B and 24C, FIGS. 18, 22, 24A,24B and 24C best illustrate the inner shaft member 4800 includes atleast one additional aperture, e.g., at least proximal locking slot4711, or additionally at least proximal locking slot 4712 as shown, thatis defined in the inner shaft member 4800. The proximal locking slots4711, 4712 extend partially along the longitudinal direction (axis“A”-“A”) of the inner shaft member 4800 and may be disposed proximallyfrom the one or more apertures, e.g., distal locking slots 4811, 4812,that are disposed distally from the proximal end 4910.

The one or more proximal locking slots 4711, 4712 are configured toenable inner shaft stop member 4150 to be disposed to slide on the innershaft member 4800 and to be movable along the longitudinal direction(axis “A”-“A”) of the inner shaft member 4800. Inner shaft stop member4150 is disposed proximally of the drive collar member 4840 and on theinner shaft member 4800.

The one or more proximal locking slots 4711, 4712 are also disposedproximally of the drive collar member 4840. The one or more proximallocking slots 4711, 4712 are configured to enable the inner shaft stopmember 4150 to engage in the proximal locking slots 4711, 4712 and tolimit movement of the inner shaft member 4800 along the longitudinalaxis “A”-“A” following insertion of spring member 489 on the inner shaftmember 4800 between the drive collar member 4840 and the inner shaftstop member 4150. The spring member 489 defines a proximal end 4891 anda distal end 4892.

The one or more proximal locking slots 4711, 4712 may be configured inan L-shape, or as shown in FIGS. 18, 22, 24A, 24B and 24C in a T-shapehaving proximal sections 4711 a, 4712 a and distal sections 4711 b, 4712b configured such that the open area of the proximal sections 4711 a,4712 a is less than the open area of the distal sections 4711 b, 4712 b.

As described in more detail below with respect to FIGS. 19A and 19B,such a configuration of the locking slots 4711, 4712 enables the innershaft stop member 4150 to limit further axial movement of the innershaft member 4800. More particularly, the inner shaft stop member 4150is disposed to slide on the inner shaft member 4800 first in a directionrelative to the longitudinal axis “A”-“A” defined by the inner shaftmember 4800 (see FIG. 24B, arrow F1) to become engaged first with theone or more distal portions 4711 b, 4712 b. Following engagement withthe one or more distal portions 4711 b, 4712 b, the inner shaft stopmember 4150 then moves proximally in a direction along the longitudinalaxis “A”-“A” defined by the inner shaft member 4800 (see FIG. 24B, arrowF2) to engage the one or more proximal portions 4711 a, 4712 a of theproximal locking slots 4711, 4712 following insertion of the springmember 489, in a compressed configuration, on the inner shaft member4800 between the drive collar member 4840 and the inner shaft stopmember 4150. Extension of the spring member 489 pushes inner shaft stopmember 4150 proximally into the proximal portions 4711 a, 4712 a tolimit movement of the inner shaft member 4800 along the longitudinalaxis “A”-“A”.

In one embodiment, the direction relative to the longitudinal axis“A”-“A” includes a direction transverse to or crossing the longitudinalaxis “A”-“A”, such as vertically downward as shown by arrow F1 in FIG.24B.

As best shown in FIGS. 19A and 19B, the inner shaft stop member 4150 mayengage the one or more proximal locking slots 4711, 4712 via an aperture4152 defined by the inner shaft stop member 4150 to impart a generallyU-shaped configuration to the inner shaft stop member 4150. At least oneprojection, e.g., projections 4154′ and 4154″ that are disposed onopposing inner surfaces 4156′, 4156″, project inwardly within aperture4152 and effect the engagement of the inner shaft stop member 4150 withthe one or more proximal portions 4711 a, 4712 a of the proximal lockingslots 4711, 4712, respectively, to limit further proximal axial movementof the inner shaft stop member 4150. In one embodiment, the inner shaftstop member 4150 is reciprocally movable along the longitudinal axis“A”-“A” of the inner shaft member 4800.

As best illustrated in FIGS. 21A and 21B, the drive collar member 4840may include a proximal rim 4846 that extends concentrically around, andprojects radially from, outer diameter D″ of the cylindrical member 4844of drive collar member 4840.

The drive collar member 4840 may further include a projection 4848 thatextends proximally from the drive collar member 4840 and which isconfigured to engage in an aperture 4892′ defined in the distal end 4892of the spring member 489 when the spring member 489 is inserted on theinner shaft member 4800 between the drive collar member 4840 and theinner shaft stop member 4150 (see FIG. 17).

In a similar manner, as best illustrated in FIGS. 17, 19A and 19B, theinner shaft stop member 4150 may further include a projection 4158 thatextends distally from the inner shaft stop member 4150 and is configuredto engage in an aperture 4891′ defined in the proximal end 4891 of thespring member 489 when the spring member 489 is inserted on the innershaft member 4800 between the drive collar member 4840 and the innershaft stop member 4841.

As best illustrated in FIG. 25, the engagement of the proximal anddistal ends 4891 and 4892 of the spring member 489 in the mannerdescribed enhances the ability of the connection mechanism 4760 todeliver a consistent axial force by reducing the probability that thespring member 489 will become misaligned with respect to thelongitudinal axis “A”-“A”. The engagement of the drive collar stopmember 4841 and the inner shaft stop member 4150 in the manner describedfurther enhances the ability of the connection mechanism 4760 to delivera consistent axial force by further reducing the probability that thespring member 489 will become misaligned with respect to thelongitudinal axis “A”-“A”. Therefore, the connection mechanism 4760yields a simplified spring load mechanism for delivering shaft load of asurgical instrument.

The foregoing description of FIGS. 16-25 also describes a method ofmanufacturing the connection mechanism 4760 for a surgical instrument toyield at least the same advantages as described above. As best shown inFIGS. 18, 22, 24A, 24B, and 24C, the method includes moving the drivecollar stop member 4841 longitudinally along inner shaft member 4800(e.g., in the direction of axis “A”-“A”), engaging the drive collar stopmember 4841 in at least one aperture defined in the inner shaft member4800, e.g., distal locking slot 4811 or additionally at least distallocking slot 4812, to limit further longitudinal movement of the drivecollar stop member 4841, and moving drive collar member 4840longitudinally along the inner shaft member 4800 until the drive collarstop member 4840 limits further longitudinal movement of the drivecollar member 4840. The method may include moving the drive collar stopmember 4841 in the direction relative to the longitudinal axis “A”-“A”so as to engage by shifting or dropping, e.g., see FIG. 24B, arrow E2,into one or both of the distal locking slots 4811, 4812 to limit furtherlongitudinal movement of the drive collar stop member 4841.

As best illustrated in FIGS. 20A, 20B, 24A, 24B and 24C, the method mayinclude retaining the inner shaft member 4800 in the lower portion 4842″of the aperture 4842 defined in the drive collar stop member 4841 as thedrive collar stop member 4841 moves distally along the longitudinaldirection “A”-“A” of the inner shaft member 4800.

The method may include limiting further longitudinal motion of the drivecollar member 4840 in the direction of the proximal end 4912 of theinner shaft member 4800 by engaging the drive collar stop member 4841with the one or more apertures such as distal locking slots 4811, 4812.This engaging may be effected by shifting the drive collar stop member4841 in a direction relative to the longitudinal movement of the drivecollar stop member 4841, e.g., by shifting or dropping into engagement(see FIG. 24B, arrow E2) first with the proximal sections 4811 a, 4812 aand then with the distal sections 4811 b, 4812 b (see FIG. 24B arrow E3)to limit further longitudinal motion of the drive collar member 4840 inthe direction of the proximal end 4912 of the inner shaft member 4800.

In one embodiment, as best shown in FIGS. 20A, 20B, 24A, 24B and 24C,the drive collar stop member 4841 defines at least one portion having aweight density differing from at least another portion having anotherweight density, e.g., as explained above defining at least one portion4841′ having a weight density differing from at least another portion4841″ having another weight density. The method may include shifting ofthe drive collar stop member 4841 being effected by the difference inweight densities. For example, the method includes disposing the threeapertures 4845 a, 4845 b and 4845 c defined by the upper portion 4841′,respectively, as arcuate segments forming a generally concentricconfiguration around the central aperture 4842.

In contrast, as can be appreciated from the description above, themethod includes configuring the lower portion 4841″ as a solid membersuch that the weight density exceeds the weight density of the upperportion 4841′ that defines the apertures 4845 a, 4845 b, 4845 c. Againas described above, the method includes effecting the movement orshifting of the drive collar member 4841 in a direction relative to thelongitudinal axis “A”-“A” defined by the inner shaft member 4800 (seeFIG. 24B, arrow E2) by the difference in weight densities to becomeengaged first with the proximal sections 4811 a, 4812 a and then withthe distal sections 4811 b, 4812 b to limit further longitudinal motionof the drive collar member 4840 in the direction of the proximal end4912 of the inner shaft member 4800 (see FIG. 24B, arrows E1 and E3).Again, as can be appreciated, this facilitates alignment and assemblyduring manufacturing.

As best shown in FIGS. 16, 17, 24A, 24B and 24C, the method may includeinserting spring member 489 in a compressed configuration on the innershaft member 4800 and moving the spring member 489 longitudinally alongthe inner shaft member 4800 to contact the drive collar member 4840 tolimit further longitudinal movement of the spring member 489.

As best shown in FIG. 24B, the method may include moving inner shaftstop member 4150 in the direction relative to the longitudinal movementof the drive collar stop member 4841 along the inner shaft member (seeFIG. 24B, arrow F1). The method may include also engaging the innershaft stop member 4150 in the additional aperture, e.g, proximal lockingslot 4711 or additionally proximal locking slot 4712, so as to limitlongitudinal movement of the inner shaft stop member 4150 when thespring member 489 contacts the inner shaft stop member 4150 uponextending from the compressed configuration.

The method may include moving the inner shaft stop member 4150 in thedirection of the longitudinal movement of the drive collar member (seeFIG. 24B, arrow F2) to engage with the one or more additional apertures,e.g., proximal locking slots 4811 and 4812 to limit further longitudinalmovement of the inner shaft member 4800.

As best illustrated in FIGS. 16, 17, 21A, 21B and 25, the method mayinclude engaging the projection 4848 that extends proximally from thedrive collar member 4840 within the aperture 4892′ defined in the distalend 4892 of the spring member 489 when the spring member 489 is insertedon the inner shaft member 4800 between the drive collar member 4840 andthe inner shaft stop member 4150. The method may also include engagingthe projection 4158 that extends distally from the inner shaft stopmember 4150 within the aperture 4891′ defined in the proximal end 4891of the spring member 489 again when the spring member 489 is inserted onthe inner shaft member 4800 between the drive collar member 4840 and theinner shaft stop member 4150.

Referring particularly to FIGS. 19A and 19B, the method may includedefining an aperture in the inner shaft stop member 4150 to impart agenerally U-shaped configuration to the inner shaft stop member, e.g.,defining aperture 4152 in inner shaft stop member 4150, and defining atleast one projection projecting inwardly, e.g., projection 4154′ and, inone embodiment, projection 4154″ within the aperture 4152. The engagingof the at least one additional aperture, e.g., proximal locking slots4711 and 4712, is effected by engaging the one or more projections 4154′and 4154″, respectively, with the one or more additional apertures suchas proximal locking slots 4711 and 4712.

As best illustrated in FIGS. 18, 22, 24A, 24 b and 24C, those skilled inthe art will recognize and understand that additional method ofmanufacturing steps may be directed to, for example, configuring theproximal sections 4711 a, 4712 a and distal sections 4711 b, 4712 b ofthe proximal locking slots 4711, 4712 such that the open area of theproximal sections 4711 a, 4712 a is less than the open area of thedistal sections 4711 b, 4712 b, as well as to the configuring of theproximal sections 4811 a, 4812 a and distal sections 4811 b, 4812 b ofthe distal locking slots 4811, 4812 such that the open area of theproximal sections 4811 a, 4812 a is greater than the open area of thedistal sections 4811 b, 4812 b. Those skilled in the art will alsorecognize that other analogous method of manufacturing steps may bedirected to other features of the present disclosure as described abovewith respect to FIGS. 16-25.

The method of manufacturing in the manner described effects theengagement of the proximal and distal ends 4891 and 4892 of the springmember 489 which enhances the ability of the connection mechanism 4760to deliver a consistent axial force by reducing the probability that thespring member 489 will become misaligned with respect to thelongitudinal axis “A”-“A”. The method of manufacturing in the mannerdescribed also effects the engagement of the drive collar stop member4841 and the inner shaft stop member 4150 which further enhances theability of the connection mechanism 4760 to deliver a consistent axialforce by further reducing the probability that the spring member 489will become misaligned with respect to the longitudinal axis “A”-“A”.Therefore, the method of manufacturing connection mechanism 4760 yieldsa simplified spring load mechanism for delivering shaft load of asurgical instrument.

In one embodiment of the method of manufacturing, the drive collar stopmember 4841 is installed on the inner shaft member 4800 by manuallymoving the drive collar stop member 4841 and the drive collar member4840 along the inner shaft member 4800 to engage the drive collar stopmember 4841 in the appropriate apertures as described above and also bymanually moving inner shaft stop member 4150 vertically downward toengage in the appropriate apertures as described above. Alternatively,these same manufacturing steps may be performed automatically viamechanical or robotic mechanisms such as are already known in the art orto become known in the art.

Similarly, the spring member 489 may be installed on the inner shaftmember 4800 manually or, alternatively, automatically via mechanical orrobotic mechanisms such as are already known in the art or to becomeknown in the art.

The method of manufacturing connection mechanism 4760 as described aboveis significantly advantageous over the prior art because the method doesnot require attaching a mandrel to the inner shaft member or attachingE-clips fasteners. Hence, there are considerable cost savings realizedby eliminating the need to attach a mandrel to the inner shaft memberand the material cost of the mandrel itself.

Since the apertures and other features of the inner shaft member may becut directly into the inner shaft member, reduced tolerances and moreprecise dimensions may be realized.

The inner shaft member, the drive collar member, the drive collar stopmember, the spring and the inner shaft stop member are assembled fromthe proximal end of the surgical instrument. The apertures such as thedistal and proximal locking slots are configured and dimensioned toprevent incorrect insertion of the drive collar stop member into theproximal locking slots and incorrect insertion of the inner shaft stopmember into the distal locking slots.

The method of manufacturing reduces part count as compared to connectionmechanisms in prior art surgical instruments, which lowers costs anddecreases assembly time. The weight imbalance of drive collar stopmember allows the drive collar stop member to automatically slide on theinner shaft member during assembly always in the same orientation andlock together with the inner shaft member during assembly, thus savingtime and assembly steps. The method of manufacturing also eliminates theneed for through pins that can cut the electrical wires to the jawmembers, and which increase assembly time and part count.

Additionally, the connection mechanism components, particularly thedrive collar stop member and the inner shaft stop member, may bemanufactured by the die-casting or powder metallurgy process, which isan inexpensive process for making components.

As a result, the method of manufacturing connection mechanism 4760results in a connection mechanism 4760 that, for the reasons describedabove, yields a simplified spring load mechanism for delivering shaftload of a surgical instrument.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely as examplesof particular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A surgical instrument, comprising: a housing; anelongated shaft extending from the housing and defining a longitudinalaxis, the elongated shaft defining at least one aperture; a drive collarstop engaged within the at least one aperture to limit movement of thedrive collar stop along the elongated shaft; a drive collar configuredto abut the drive collar stop to limit distal movement of the drivecollar along the elongated shaft; a shaft stop engaged within at leastone additional aperture defined by the elongated shaft to limit proximalmovement of the shaft stop; a spring disposed on the elongated shaftbetween the shaft stop and the drive collar and configured to beretained in a compressed condition by the shaft stop; and a projectionextending distally from the shaft stop and configured to engage aproximal end portion of the spring.
 2. The surgical instrument accordingto claim 1, wherein the drive collar is configured to engage the springto limit distal movement of the spring along the elongated shaft.
 3. Thesurgical instrument according to claim 1, wherein the shaft stop isconfigured to be moved transverse to the longitudinal axis to engagewithin the at least one additional aperture.
 4. The surgical instrumentaccording to claim 1, wherein the drive collar includes a projectionextending proximally therefrom configured to engage a distal end portionof the spring.
 5. The surgical instrument according to claim 1, whereinthe drive collar stop defines an aperture and at least one projectionextending within the aperture, the at least one projection of the drivecollar stop is engaged with the at least one aperture defined by theelongated shaft.
 6. The surgical instrument according to claim 5,wherein the at least one projection of the drive collar stop is engagedwithin a distal portion of the at least one aperture.
 7. The surgicalinstrument according to claim 1, wherein the shaft stop defines anaperture and at least one projection extending within the aperture, theat least one projection of the shaft stop is engaged with with the atleast one additional aperture defined by the elongated shaft.
 8. Thesurgical instrument according to claim 7, wherein the at least oneprojection defined by the shaft stop is engaged within a proximalportion of the at least one additional aperture.
 9. The surgicalinstrument according to claim 1, further comprising: an end effectordisposed at a distal end portion of the elongated shaft, the endeffector including: a first jaw member including a first pair oflaterally spaced flanges; and a second jaw member including a secondpair of laterally spaced flanges disposed between the first pair oflaterally spaced flanges.
 10. The surgical instrument according to claim1, further comprising a knife movable along the longitudinal axisconfigured to cut tissue.
 11. The surgical instrument according to claim10, further comprising a knife guide defining a longitudinal slotconfigured to receive the knife therethrough.
 12. The surgicalinstrument according to claim 1, wherein the elongated shaft is axiallydisposed within an outer shaft member.
 13. A surgical instrument,comprising: a drive collar stop engaged within at least one aperturedefined by an elongated shaft; a drive collar disposed on the elongatedshaft and abutting the drive collar stop to limit distal movement of thedrive collar along the elongated shaft; a spring disposed around theelongated shaft and configured to engage the drive collar to limitdistal movement of the spring along the elongated shaft; a shaft stopengaged within at least one additional aperture defined by the elongatedshaft to limit proximal movement of the elongated shaft and retain thespring in a compressed condition between the shaft stop and the drivecollar; and a projection extending distally from the shaft stop andconfigured to engage a proximal end portion of the spring.
 14. Thesurgical instrument according to claim 13, wherein the drive collar stopdefines an aperture and at least one projection extending within theaperture, the at least one projection of the drive collar stop isengaged with the at least one aperture defined by the elongated shaft.15. The surgical instrument according to claim 13, wherein the drivecollar includes a projection extending proximally therefrom configuredto engage a distal end portion of the spring.
 16. The surgicalinstrument according to claim 13, wherein the shaft stop defines anaperture and at least one projection extending within the aperture, theat least one projection of the shaft stop is engaged with the at leastone additional aperture defined by the elongated shaft.
 17. The surgicalinstrument according to claim 13, wherein the elongated shaft is axiallydisposed within an outer shaft member.
 18. The surgical instrumentaccording to claim 13, further comprising a knife movable along alongitudinal axis defined by the elongated shaft configured to cuttissue.
 19. The surgical instrument according to claim 18, furthercomprising a knife guide defining a longitudinal slot configured toreceive the knife therethrough.
 20. A surgical instrument, comprising: adrive collar stop disposed around an elongated shaft; a drive collardisposed around the elongated shaft and abutting the drive collar stopto limit distal movement of the drive collar along the elongated shaft;a spring disposed around the elongated shaft and configured to engagethe drive collar to limit distal movement of the spring along theelongated shaft; a shaft stop disposed around the elongated shaft andconfigured to limit proximal movement of the elongated shaft and retainthe spring in a compressed condition between the shaft stop and thedrive collar; and a projection extending from the shaft stop andconfigured to engage the spring.